The present invention relates to the field of writing instruments, and more particularly the ergonomics thereof.
In the present context <<writing instrument>> means any instrument for manually tracing writing on an adapted surface. Examples of writing instruments are for example pencils, pens, ballpoint or felt-tipped pens, and even adapted styluses. All these writing instruments typically have an elongated form for gripping a front part of the writing instrument between the tips of the thumb and at least one of the index and middle fingers, while a rear part is supported in the grasping angle between the thumb and the index finger to stabilise the writing instrument in the hand. To facilitate this grasping, in particular for school pupils when learning to write, different writing instruments of ergonomic design have been proposed.
Some of these ergonomic writing instruments, such as for example that disclosed in international patent application WO 01/97653, have a front body with an asymmetrical and ergonomic grasping segment relative to a first longitudinal plane, and an asymmetrical rear body relative to a second longitudinal plane, different to the first longitudinal plane. The grasping segment is adapted to be gripped between the tips of the fingers, while the asymmetry of the rear body better matches the form of the grasping angle, that is, the space between the thumb and the index finger of one hand.
However, one disadvantage of such ergonomic writing instruments is that due to their asymmetry they can be adapted to usage with the left hand or right hand only. Different instruments must therefore be produced for right-handed and left-handed people, with everything this involves in terms of production and storage costs, as well as disadvantages for users.